This invention relates generally to disposable diapers, and more particularly to disposable diapers such as infant and adult diapers for the absorption and containment of urine and other body exudates.
It is well known to make a liquid-absorbent pad disposed between a topsheet and a backsheet of a disposable diaper by covering upper and lower surfaces of an absorptive core, made of fluff pulp, for example, with upper and lower absorptive sheets such as tissue sheets. It is also well known to bond these absorptive sheets to the surfaces of the absorptive core by means of adhesive agent such as hot melt adhesive. The adhesive has conventionally been applied on respective inner surfaces of these absorptive sheets in the form of a plurality of lines extending in parallel to one another or a plurality of spots. By covering the absorptive core in this manner, fluff pulp is prevented from scattering in the course of production to avoid wasteful use of material and improve productivity.
However, the conventional manner of adhesive application as in the above-mentioned well known art makes it difficult to seal the absorptive core around it with the upper and lower absorptive sheets and sometimes undesirable leakage of the absorptive core material occurs through gaps of the upper and lower absorptive sheets during a process of production. To avoid this, separate adhesive exclusively for sealing purpose must be applied to portions of the sheets around the absorptive core. As a result, in addition to the adhesive used to bond the sheets to the absorptive core, the adhesive used to seal the absorptive core will be applied to the sheets. This leads to unacceptably high rigidity of the sheets which irritates the wearer's skin and degrades comfort. While it is possible to assign the respective adhesives to different regions, the equipment for production will be inevitably complicated and a cost of the product will be correspondingly increased.